So i see that when the type is webP it works fine (The image is previewed properly). It does not work when the type is octet-stream. MC with fix (89.0a1 (2021-03-26) ) The webp image shows as the type webp and the image previews properly
Bug 1699037 Comment 6 Edit History
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MC without fix e.g (89.0a1 (2021-03-23) ) The webp image shows as the type octet/stream and the image does not show on preview.